set Referrer-Policy to strict-origin

data/conf/nginx/site.conf

@@ -37,7 +37,7 @@ server {
   add_header X-Download-Options noopen;
   add_header X-Frame-Options "SAMEORIGIN" always;
   add_header X-Permitted-Cross-Domain-Policies none;
-  add_header Referrer-Policy no-referrer-when-downgrade;
+  add_header Referrer-Policy strict-origin;
 
   index index.php index.html;